Trustees



(No Model.)

2 Sheets-Sheet 1. 1

H. P. PRATT. TBLEPHQNE.

PatQn-ted Jan. 20

IINiTnn STATES HARRY l?. PRATT, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO HIMSELF, CHARLES C. BONNEY, JOHN A. HAMLIN, AND CHARLES E. BARRETT, ALL OF SAME PLACE, AND VILLIAM R. PLUM,

OF LOMBARD, ILLINOIS, TRUSTEES.

TELEPHONE.

SPECIFICATIONforming part o1 Letters PatentNo. 310,961, dated January 2O 1885.

Application tiled October 1, 1883. (No model.)

A To a/ZZ whom it may concern.-

Be it known that I, HARRY l?. PRATT, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented anew and useful Improvenient in Telephones, of which the following is a description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to that class of telephone-instruments known as receiversf and it consistsin the construction and arrangement of parts,which will be hereinafter more fully described, and pointed out in the claims.

The object of my inventionis to produce an instrument which shall more cheaply, perfectly, clearly, and distinctly reproduce vocal and other sounds and signals than has heretofore been accomplished by other instruments 2o for a like purpose. This result I attain by the use, in asuitable box or case provided with a diaphragm or plate made of iron or other suitable substancaof a coil of wire made without a core, the wire being wound tightly and Y 2 5 evenly, each convolution of which is glued or cemented to the other convolutions, so as to present an even or nearly even surface at both top and bottom. This coil I place in a box or case, the ends of the wire being electrically 3o connected in the usual manner, and'secure it firmly to the case beneath a diaphragm or plate of iron or other suitable substance. Through this coil I pass a current of electricity, which so acts upon the plate or diaphragm as to cause it to give forth sounds, speech, or telegraphic signals received over the line from the transmitting-instrumentin response to the direct action of the electric current, in clear and distinct tones, as uttered or delivered.

A core has heretofore been regarded as essential to the successful operation of a coil in a receiving-telephone instrument; but I have discovered that such core may be dispensed with to advantage, and I therefore dispense with the same, and substitute therefor asolenoid or simple coil made without a core in been otherwise attached to or connected with 5o the receiving-coil; but I do not use any such magnet in connection with my solenoid.

By my said invention I overcome the confusion of tones found in the use of other instruments, and obtain a clear and satisfactory reproduction of sounds, speech, or signals transmitted from the other end of the line, and cheapen the cost of the instrument. My invention is of especial advantage where underground wires are used.

In the accompanying drawings, which form a part of this specification, and in which similar letters of reference refer to like parts, I have shown and illustrated my invention.

Figure l represents a cross-sectional view of my telephone, showing one-half of the case cut away, the central coil being represented entire. Fig. 2 is a top view of the same, with the upper casing and ear-piece and top plate removed, so asto expose the central coil. Fig. 3 is Van elevation of the upper plate, or the one which is placed between the coil and the earpiece. Fig. 4 shows a modification having two coils instead of one. Fig. 5 also shows a modification, two coils being used the same as in Fig. et, and the diaphragm being divided into two plates instead of one. Fig. 6 represents my invention as the same may be applied for receiving telegraphic signals.

A represents the outer case of the clectro- 8o phone or telephone.

B represents the ear-piece upon one side of said case.

C indicates the coil.

D is the top plate, placed over the coil and 8 5 under the earpiece.

E is the lower plate.

F is the surrounding band by which the coil is secured or held in position.

g and h are the binding-posts with which 9o the ends of the wire composing the coil are connected.

H and I indicate the two coils in the modiiied construction shown in Figs. 4 and 5.

o' and p represent the two upper plates used in the modification shown in Fig. 5.

The coil C should be wound tightly and evenly, with each convolution glued or cemented, so as to present an even or nearly even surface at both top and bottom. Over the coil C, I place a suitable plate, D, preferably of iron, and in the form shown in Fig. 3. Both of the plates D and E may, however, be made round, square, or of such shape as will answer the desired purpose. I do not coniine myself to the use of a single coil, nor of a sinplate, nor to the precise construction of coils and plates shown in the drawings, but desire to secure my right to allforms and modifications of the instrument which come within the principle of my invention. For example, I contemplate the use of a secondary plate or diaphragm on the farther side of the solenoid or simple coil, as shown in Fig. l; and, instead of a single coil such as I have described, two or more may be used in connection and combination with such plate or plates. The shape and thickness of the plates may be varied to suit the size and work of the instrument, all such variations being mechanical details.

The modifications shown in Figs. 4: and 5 need but little explanation, and consist in two coils instead of one in the same case, and held in position by surrounding bands, a single plate being used over the same.

My telephone may also be attached to a wire over which telegraphic signals are transmitted by the use of an ordinary telegraph-key. The person receiving the communication may, by holding my telephone to the ear, readily read such signals, and in this manner the noise and confusion which exist in all telegraph-cineos may be overcome, and an unauthorized person be prevented from securing information, as he can easily do when an ordinary relay and sounder are used. Fig. 6 is designed to show this application of my invention.

The plate or diaphragm in my instrument is non-polarized. p

I use the term non-polarized 7 in the application and in the claims to denote the condition of the diaphragm when not in action, and to distinguish my instrument from others speech, or signals, t-he combination of the case I A, the ear-piece B, the coil @,withont a core, and the non-polarized plate D, made of iron or other suitable substance, all arranged, constructed, and operated substantially as described, and for the purpose set forth.

3. In an instrument for receiving sounds or signals, l[he combination of the case A, the earpiece B, the coil C, without a core, the nonpolarzed plate D, made of iron or other suitable substance, andthe plate E, constructed substantially as described, and for the purpose set forth.

4. In a telephone, the combination of the case A, the non-polarized plate D, made of iron or other suit-able substance, and one or more coils without a core or cores, substantially as described, and for the purpose specified.

5. In an instrument for receiving sounds, speech, or signals, a coil or coils without a core or cores, in combination with one or more non-polarized plates or diaphragms, made of iron or other suitable substance, placed between said coil or coils and the car-piece,

substantially as described, and for the purpose set forth.

(i. In a telephone receiving-instrument, the combination of thecase A, ear-piece B, nonpolarized diaphragms or plates, coil C, support F, and binding-posts g and l1, substantially as described, and for the purpose set forth.

HARRY I. PRATT. lVitnesses:

FREDERICK C. GooDwrN, 0. WV. BOND. 

